1. Field of the Invention
The present invention relates to fishing rods and is directed particularly to improvements in ferrules for fiber-reinforced plastic fishing rods.
2. Prior Art
It is a common practice to manufacture lengthy fishing rods such as fly casting type fishing rods, surf rods and the like, in multiple sections with various devices for detachably securing and coaxially aligning one section to the other thereby permitting the rods to be easily dismantled for transit and storage and the like and thereafter be reassembled for use. In the past, it had been the general practice with both bamboo and fiberglass fishing rods to provide some type of metallic ferrule or sleeve connector at certain longitudinal locations along the fishing rod to provide for detachably securing fishing rod sections one to the other. More recently, ferrules have been constructed of plastics and fiber-reinforced plastics for use particularly in conjunction with fiberglass fishing rods. Thus, in U.S. Pat. No. 3,152,820 there is described a thermo-plastic fishing rod ferrule that has a critical set of dimensions. As is known in the art, however, thermo-plastic resins such as the type described in the aforementioned patent are subject to creep and cold flow with the concomittant result that the flex or performance characteristics of the ferrule change considerably and indeed the ferrule is even subject to failure with time.
In U.S. Pat No. 3,469,338 a fiberglass reinforced ferrule section is described in which woven glass fabric is employed in reinforcing the plastic ferrule. The fabric is so arranged that the glass fibers are at an angle of 90.degree. with respect to each other. Indeed, some of the glass fibers extend longitudinally of the fishing rod and the remaining fibers extend at substantially right angles to the axis of the rod. The deficiency in this type of construction is that it tends to leave a flat spot in the rod when under load. Such construction suffers from the further disadvantage in that it does not permit uniform stress distribution which contributes to creep failure.
In graphite fiber-reinforced sectional fishing poles the disadvantages of the foregoing types of ferrules are greatly enhanced because of the strength characteristics of the graphite which transmit significant forces to the ferrule section when the fishing rod is under load resulting in failure of the ferrule and/or loss in the bending profile of the rod. A bending profile and sensitivity similar to a unitary or one-piece flexible rod is a commercially important criteria for multisectional fishing poles of all types.